What's the word I'm thinking of? Today, it's....
A dog with a curly tail
"Be thy mouth or black or white,
Tooth that poisons if it bite;
Mastiff, greyhound, mongrel grim, 50
Hound or spaniel, brach or lym;
Or bobtail tike or trundle-tail;
Tom will make them weep and wail:
For, with throwing thus my head,
Dogs leap the hatch, and all are fled.
--William Shakespeare, King Lear, Act III, scene VI
Who let the trundle-tails out?